It's extraordinary video inside a monster tornado, footage of a kind never seen before.
EF-4 is just one category below the deadly EF-5 that ripped through Oklahoma and caused such terrible devastation.
So, can anyone possibly survive fury this intense?
The video was shot from inside a reinforced storm chaser tank known as the Tornado Intercept Vehicle. It's designed to withstand some of the fiercest twisters imaginable, but that tornado pushed it to the limit.
Storm chaser Sean Casey was in the vehicle when the monster tornado engulfed it.
He said, "It was the roughest tornado we've ever been in. Maybe five, ten miles per hour more wind and it might have been an unhappy ending."
Even the heavily armored vehicle sustained damaged.
He said, “The side mirrors are smashed, instrumentation is gone, so today we are cleaning up"
Now we know what it's like in the belly of the beast.